Republican presidential candidate Ted Cruz on Tuesday accused Donald Trump of “whining” about the delegate process, in a feisty interview with Fox News’ Sean Hannity in which the Texas senator insisted the only ones raising concerns about the rules are Trump backers.

Cruz, and the Republican Party as a whole, for days have battled claims that the nominating process is “rigged.” Trump still leads comfortably in the overall delegate count, but Cruz has strengthened his position by getting allies elected to the delegate slates in a number of states – including those that never held traditional primaries or caucuses.

After Hannity pointed out that voters are sounding off on social media about how confusing the process is, Cruz responded: “The only people asking this question are the hardcore Donald Trump supporters.”

In a heated exchange, Cruz then called the claims about him winning “voterless” elections “nonsense.” And he said the Trump campaign does not know “how to organize on the grassroots,” especially when it comes to the actual selection of individual delegates to the convention.

Trump, though, reportedly is reorganizing his campaign staff with an eye toward the upcoming contests and has voiced confidence in his ability to take on Cruz’s operation.

“We’re bringing in very high-level people,” he told Fox News’ “Fox & Friends” on Tuesday morning. “We’d like to see if we can close it out.”